Allergy myths

The Pediatric Insider

© 2009 Roy Benaroch, MD

I’m writing from my hotel in Washington, DC at the American Academy of Pediatrics annual national convention. It’s definitely pediatrics—some of the exhibitors were handing out lollipops today, and one even brought along a puppy to play with!

One of the best talks I heard today was from an allergist, reviewing the science behind allergy testing, when to do it, what it means, etc. But the biggest eye-opener for me occurred during the questions afterwards. I’m embarrassed to say that it’s obvious that many pediatricians haven’t got a clue about how to diagnose allergies. And if the peds aren’t getting it right, where does that leave the parents? So I’m going to skip right past your pediatrician, and today reveal…the deep dark insider story. It’s time for a top ten list, the top ten myths about allergy that pediatricians are getting wrong.

#1 Food allergies are common

Many people think they’re allergic to foods, but rigorous studies using the best, most reliable diagnostic tools find food allergies to be present in about 2-8% of the population. Most of these reactions are mild. True, life-threatening food allergies are quite rare—in the United States, about 150 people die each year from food allergies, which is only a little higher than the number of people struck by lighting.

#2 Most reactions to food are allergies

An allergy refers to a specific kind of reaction, most commonly hives or wheezing. Other, more common reactions include lactose intolerance (an inability to digest milk sugar, leading to abdominal cramps and diarrhea) and gastroesophageal reflux related to spicy or acidic foods. The distinction is important because rare, very serious allergic reactions can occur. If the reaction was not allergic in nature, it will not possibly be life-threatening if exposure occurs again.

#3 Most reactions to medicines are allergies

The most common adverse reaction to a medication is a rash, but these are usually not caused by allergy (the only common truly allergic rash is hives, which are raised, itchy areas that move about the body.) Most people labeled as “allergic” to penicillin are not in fact allergic, and can safely use this medication. Only a careful history and exam can determine this—there is no accurate test to confirm or refute true drug allergies. If you or your child is thought of as drug allergic, review the exact circumstances with your physician to see if it is a good idea to try the medication again (do NOT do this on your own!)

#4 People who are allergic to a medicine should never take it again

Certainly, if a life-threatening reaction occurred you need to be very careful. And be much, much more wary of medications given as a shot or intravenously (I’m not sure anyone has ever died as a result of an allergic reaction to oral penicillin.) But unless the reaction was a true allergic reaction, usually manifested by hives or wheezing, a medication can usually be given safely in the future (again, do NOT do this on your own!)

#5 If you’re allergic, but can tolerate “a little bit” of the allergic trigger, it’s good to keep taking that little bit

This one was new to me, but someone brought it up. The idea is that there may be some people who seem to be able to tolerate “a little bit” of their trigger, let’s say a little cheese, but has a belly ache if they consume a lot of milk. So maybe it’s OK for them to take that little bit.

No! First, you have to ask, is the patient really allergic? In my cheese example, the patient probably has lactose intolerance, not an allergy—so it’s fine to take some dairy, if it doesn’t hurt.

But in a truly allergic individual—one with true allergic symptoms—even consuming a little bit of the trigger is going to perpetuate the allergy and make it less likely to outgrow it. So if your child is really allergic, don’t cheat!

#6 People with any history of egg allergy shouldn’t get a flu shot

There is a tiny amount of egg protein left over from the manufacturing process of making influenza vaccines. If your child has a severe egg allergy, flu vaccines cannot be given; but for children with far-more-common mild reactions, flu vaccinations are safe and a good idea. If in doubt, egg allergy testing can be done, or the flu shot can be given at the allergist’s office.

#7 People with egg allergy shouldn’t get an MMR vaccine

This just isn’t true. It’s a myth. MMRs can safely be given to anyone with egg allergies.

#8 Allergy testing can tell you if a child is allergic to something

Hoo boy, pediatricians seem to miss this one! The way to know if a person is allergic is entirely in the history: do symptoms of allergy occur upon exposure? If they do, that’s allergy; if they don’t, that is not allergy. If the history is clear, the diagnosis is nailed, done, confirmed, and set. No tests are needed; in fact, tests are quite likely to confuse the picture.

Allergy tests are for when the history is not clear, to help separate exposures that are “likely” from “less likely”, so that further history can be explored and attempts at avoidance attempted to see what the response is. Allergy testing, either with blood tests or skin testing, is far too inaccurate to be used in any other way.

Be especially wary of web-based labs that promise extensive allergy testing to investigate vague symptoms like weight gain, abdominal pain, low energy, fatigue, and behavior problems. These symptoms are not caused by allergy, though fraudulent testing will inevitably lead to false positives and incitements to purchase detoxifying supplements. This is quackery, and expensive quackery at that. Stay away!

#9 Hives are usually caused by allergies to foods

In adults, this might be true; but in kids, hives are more often triggered by minor infections than by food exposures. Sure, if there are hives you ought to think about potential new foods, and if there is a correlation you ought to look into that. But in the majority of cases in pediatrics, isolated or even recurrent episodes of hives are not necessarily from food allergies.

#10 Specific allergies run in families

“Don’t give him penicillin! Mom’s allergic!” While the predisposition to allergies, asthma, and hay fever run in families, it isn’t to the same specific trigger. Junior has a mom with shrimp allergies? That means that he might more likely have food allergies of his own, but not more likely to shrimp than to peanut or egg or anything else. Same for medication allergies.

If your physician is telling you myths from the above list, it’s time to ask for a referral to an allergist to get the best information. If it’s an allergist tell you one of these myths, well, I’m stumped.

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2 Comments on “Allergy myths”

  1. Collyn Alford Says:

    Wow- eye opening read, especially to a parent who has done the allergy “thing” with their child and who as an adult all of the sudden developed an “allergy” to tree nuts. Interestingly enough, our son would get sick after getting allergy shots and when I had skin testing and bloodwork for mine, it all came back negative. Thanks for sharing what you learned!

    Like


  2. This is superb and really informative article about the different factors related to allergy. Yaa!! that’s right Food and Medicine are the most common cause for allergy.

    Thanks
    Oliver

    Like


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